Electroslag remelting process

ABSTRACT

An electroslag remelting process in in which fused consumable electrodes are fed into a mould, the electrodes being mounted movably and stationary with respect to the mould and connected to a power source according to a bifilar circuit. The electrodes are arranged in the mould space in parallel rows alternating in such a manner that one row is composed of the electrodes coupled to one leadout of the power source and the other of those coupled to another leadout thereof.

United States Patent 1191 Paton et a1. July ,9, 1974 1 1 ELECTROSLAG REMELTING PROCESS In entors: oris Evgen ev c a on, ulitsa 5.1.8.311- I KOtSjUbinSkOgQ, Kv. Boris lzrailevich Medo'var, bulvar Lesi 1 o arc 1 34 Ukrainki, 2, kv. 8; Vladimir Prokhorovich Andreev, prospekt 1 1 References Cited l h l 5 gy UNITED STATES PATENTS f g 2 'gi kv 106 1,092,764 4/1914 Buckman, Jr 13/9 1,113,778 10/1914 Gray ..13/9 z g g gg 3,665,081 5/1972 Paton a a1. 13/9 ES Jury Vasilievidh obolet ulitsa Prim ary Examiner-Roy N. Envall, Jr. figfizggfifigi i i 2L2 3 z Attorney, Agent, or FirmHolman and Stern 1 a 45, kv. 17, both of Kolpino Leningradskoi oblasti; Evgeny [57'] ABSTRACT Tikhonovich Dolbenko, ulitsa An electroslag remelting process in in which fused Garibaldi, l0, kv. 3; Viktor Iconsumableelectrodes are fed into a mould, the elec- Vasilievich Chernykh, ulitsa ,trodes being mounted movably and stationary with re- Belomorskaya, l8, korpus 4, kvl 51, spect to the mould and connected to a power source bothof Moscow, all of U.S.S.R according to a bifilar circuit. The electrodes are art ranged in the mould space in parallel rows alternating [22] Filed 1973 [in such a manner that one row is composed of the [21] Appl. No: 354,436 electrodes coupled to one leadout of the power source and the other of those coupled to another leadout [30] Foreign Application Priority Data ihereof' Apr. 29, 1972 U.S.S.R 1778702 5 Claims, 3 Drawing Figures BACKGROUND OF-THE INVENTION The present invention relates to electrometallurgy and more particularly to electroslag remelting processes.

The invention is useful for the production of rectangular ingots to be rolled into sheets 200 300 mm thick and for the manufacture of cast blanks having an intricate shape.

An electroslag remelting process carried out by feeding fused consumable electrodes into a cooled metallic mould is known in the art.

With the above process two groups of consumable electrodes are taken, each of the groups being made up of one movable electrode and one stationary electrode with respect to the mould, the electrodes being connected to a power source according to a bifilar circuit.

The known process enables ingot slabs featuring a large width-to-thickness ratio to be manufactured.

A disadvantage of the known process. resides in the possibility of contact between the edges of the movably mounted electrodes and mould walls which may lead to the walls being burnt through. Moreover, the uses of this process are limited, insofar as the fabrication of a large ingot with a large cross-section and a thicknessto-width ratio close to l is impractical.

SUMMARY OF THE INVENTION These objects are accomplished in an electroslag remelting process of fused consumable electrodes are fed into a cooled metallic mould, the electrodes being connected to a power source according to a bifilar circuit before the initiation of the process and with some of them being mounted so as to be capable of vertical dis placement in relation to the mould, according to the invention, the movably and stationary mounted electrodes are arranged in the mould in parallel rows with respect to its horizontal plane, the rows alternating in such a manner that the electrodes connected to' one transfer winding leadout are arranged in one row and those connected to the other leadout are arranged in the other row, the total cross-sections of the electrodes in each row being equal to each other.

The above arrangement of the electrodes ensures a uniform liberation of heat power over the entire volume of a slag bath as well as an equal fusing rate of the electrodes in each row predetermining thereby a negligible electrical unbalance. Due to the presence of a great number of drop-formation centers between the rows and a regular distribution of the heat power over the entire volume of the slag bath, a metal bath has the most favorable-shape. All this contributes to the production of ingots of high-quality metal.

It is most expedient from the technological aspect that the electrodes be arranged in the mould in two rows, the electrodes of one row being connected to one leadout of the transformer winding and those in the other row to another leadout.

The arrangement of the electrodes in two rows and the above-specified connection of the electrodes to a power source makes it possible to minimize the scope of preparatory operations.

It is most expedient that the extreme electrodes in a row be mounted in the mould stationary in relation thereto. Since all the electrodes in this row are under the same electric potential and since stationary electrodes which are reliably insulated and secured are arranged between the mould interior and the movable electrodes, melting can be carried out without the movable and stationary electrodes contacting each other and, the possibility of their touching the mould surface also being precluded.

In this case it is also possible to minimize the clearances between the electrodes arranged in one row (10-15 mm) which in turn ensures a maximum filling factor of the mould (0.8-0.9) (a ratio of cross-sectional area of the electrodes to that of the mould).

One of the features of the present invention provides that the movably mounted electrodes have smaller cross-sections than the stationary ones. l

The use of stationary electrodes with the crosssection exceeding that of the movable electrodes by several times together with a high mould filling factor enables ingots whose weight is several times the rated capacity of the machine to be produced. Thus. in an electroslag remelting machine with a capacity of 8 t, ingots measuring I600 700 mm, 25 t in weight were obtained. Where rectangular electrodes are utilized, the movable electrodes face the stationary ones with their widest sides.

Since the movable electrodes face the stationary ones with their widest sides and the mould wall with their narrowest sides, the surfaces of possible contact between the movable electrodes and the mould wall are minimized, and the most reliable electroslag remelting is ensured.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention will be better understood from a consideration of a detailed description of an exemplary embodiment thereof, taken in conjunction with the accompanying drawings, wherein:

FIG. 1 is a side view of one of possible arrangements of the groups of consumable electrodes in the mould during remelting;

FIG. 2 is a top view of one of possible arrangements of the electrodes in a rectangular cooled mould and of the transformer feeding the electrodes;

FIG. 3 is a top view of one of the electrode arrangements in the cooled mould of circular section.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The essence of the process of the invention consists in the following. Consumable electrodes are introduced into a metallic cooled mould 1 (FIG. I) mounted on a cooled base plate 2. Some of electrodes 3 are secured with respect to the mould l'and other ones (electrodes 4) are arranged so as to be capable of vertical displacement in relation to the mould l.

The electrodes 3 and 4 are arranged in the mould 1 in parallel rows a" (FIG. 2) and b in relation to its horizontal planeso that the total cross-sections of the electrodes 3 and 4 are equal to each other in cthe rows ialfi 56b1 Additionally, the total cross-sections of the movable electrodes 4 are also equal to one another in each row a and b. Then the electrodes 3 and 4 in one row a are connected to one winding leadout 5 of a transformer 6, the electrodes 3 and 4 in another row b being connected to another winding lead out 7 of the transformer 6 in such a manner that the rows a and b of the electrodes 3 and 4 are at alternating potential. Next the requisite amount of molten slag is poured into the mould 1 to form a slag bath 8 (FIG. 1) and the electroslag process is initiated.

As the electrodes are melted, the movable electrodes 4 are gradually lowered into the slag bath 8 to produce the formation of a metal bath 9. i

The electrodes are so mounted in the rows a and b" that the stationary electrodes 3 are located on both sides of each movable electrode 4. Since each row of electrodes is coupled to one leadout of the transformer winding, all the electrodes in this row are at the same potential. Hence, melting can becarried out without the movable and stationary electrodes contacting each other, and the possibility of the electrodes touching the mould wallsbeing also precluded, insofar as the spacing between the internal surface of the mould and the movable electrodes is filled with the stationary electrodes reliably insulated and secured. The latter fact enables the use of small clearances (10-15 mm) between the electrodes and internal mould wall which in turn ensures high mould filling factor.

The proposed electroslag remelting process enables the production of ingots with a large cross-section and weight exceeding that of the movable electrodes by several times (3-4) (the weight of the movable electrodes being limited by the rated capacity of the casting machine) which is attained by using the stationary electrodes with a cross-section exceeding that of the movable electrodes by several times (8-15).

As compared with known processes, the process of the present invention has the following advantages.

The movable electrodes can be introduced into the slag bath either with the help of a single electrode holder or with two holders.

In the latter case the movable electrodes can be replaced alternately during the melting operation, this being yet another factor contributing to the production of heavy ingots on low-capacity machines.

With the present process initial adjustable melting variables include voltage across all the electrodes and current magnitude in the stationary electrodes which is regulated by changing'the feed rate of the movable electrodes. All the electrodes may have either similar or different chemical composition. In the second case the ingots with a lower dopant content may be produced, this being very important in the manufacture of alloys needed for producing the consumable electrodes, since their fabrication from the above alloys by the known methods presents a problem.

FIG. 2 is a diagrammatic representation of the mould 1 having rectangular cross-section, this mould accommodating two parallel rows a and b" of electrodes 3 and 4 also having a rectangular section. The elec trodes 3 and 4 arranged in one row are connected to one leadout 5 of the winding of the transformer 6, whereas the electrodes 3 and 4 arranged in the other row b" are coupled to another winding leadout 7 of the transformer 6. ln this case the rectangular electrodes 4 which are mounted movably have their widest sides facing the electrodes 3 which are mounted stationary.

FIG. 3 is a diagrammatic representation of the mould 1 having a circular cross-section, this mould accommodating two parallel rows a" and b" of electrodes 3 and 4 respectively. Each row is composed of three electrodes, the middle one being mounted so as to move vertically with respect to the mould, while the two others are securely fixed in relation to the mould.

In this case the electrodes 3 and 4 arranged in the row a" are coupled to one winding leadout 5 of the transformer 6, the electrodes 3, 4 arranged in the row b being connected to the winding leadout 7 of the transformer 6.

What we claim is:

1. An electroslag remelting process employing fused consumable electrodes comprising the steps of:

introducing into the melting zone of a cooled metallic mould a plurality of consumable electrodes; arranging the consumable electrodes in the melting space of the mould in at least two substantially parallel rows insulated from each other and from the mould, so that the total cross-sectional areas of the consumable electrodes in each row are equal, with a predetermined number of consumable electrodes in each row being mounted stationary with respect to the mould, the remaining ones being mounted so as to be vertically displaceable relative thereto; providing electric power from a power source to the electrodes in the mould in accordance with a bitilar circuit, so that the movably and stationary mounted electrodes of a predetermined row is connected to a selected lead of the power source and the movably and stationary mounted electrodes of the other row are connected to the other lead of the power source; pouring a current-conducting slag into the melting space of the mould up to a level sufficient to make contact with the lower ends of the movably and stationary mounted electrodes; initiating the remelting process by passing an electric current from the power source through the bath of current-conducting slag, to thereby melt the electrodes; and forming a fused ingot of melted metal from the melting consumable electrodes, the movably mounted electrodes being displaced vertically downward into the slag bath for further melting thereof, so that the slag bath is gradually displaced upwardly and constantly in contact with the melted ends of the stationary mounted electrodes until the completion of remelting of the movably and stationary mounted electrodes. 2. The process as defined in claim 1, wherein said plurality of consumable electrodes are disposed in the melting space of said mould in an even number of rows, so that when two rows are present the consumable electrodes of one row are connected to one lead of the power source while the electrodes of the other row are connected to the other lead of the power source, and when the electrodes are arranged in an even number of rows more than two, the electrodes-of adjacently disposed rows are respectively connected to different leads of the power source than the electrodes of the other rows.

trodes in that row.

5. The process of claim l wherein rectangular shaped electrodes are introduced into the melting space of the mould so that the widest faces of the movably mounted electrodes face the widest faces of stationary ones.

l l l 

1. An electroslag remelting process employing fused consumable electrodes comprising the steps of: introducing into the melting zone of a cooled metallic mould a plurality of consumable electrodes; arranging the consumable electrodes in the melting space of the mould in at least two substantially parallel rows insulated from each other and from the mould, so that the total crosssectional areas of the consumable electrodes in each row are equal, with a predetermined number of consumable electrodes in each row being mounted stationary with respect to the mould, the remaining ones being mounted so as to be vertically displaceable relative thereto; providing electric power from a power source to the electrodes in the mould in accordance with a bifilar circuit, so that the movably and stationary mounted electrodes of a predetermined row is connected to a selected lead of the power source and the movably and stationary mounted electrodes of the other row are connected to the other lead of the power source; pouring a current-conducting slag into the melting space of the mould up to a level sufficient to make contact with the lower ends of the movably and stationary mounted electrodes; initiating the remelting process by passing an electric current from the power source through the bath of current-conducting slag, to thereby melt the electrodes; and forming a fused ingot of melted metal from the melting consumable electrodes, the movably mounted electrodes being displaced vertically downward into the slag bath for further melting thereof, so that the slag bath is gradually displaced upwardly and constantly in contact with the melted ends of the stationary mounted electrodes until the completion of remelting of the movably and stationary mounted electrodes.
 2. The process as defined in claim 1, wherein said plurality of consumable electrodes are disposed in the melting space of said mould in an even number of rows, so that when two rows are present the consumable electrodes of one row are connected to one lead of the power source while the electrodes of the other row are connected to the other lead of the power source, and when the electrodes are arranged in an even number of rows more than two, the electrodes of adjacently disposed rows are respectively connected to different leads of the power source than the electrodes of the other rows.
 3. The process of claim 1 wherein the extreme electrodes in each row are stationarily arranged in the mould space with respect to the mould.
 4. The process of claim 1 wherein the movably mounted electrodes of each row have a substantially smaller cross-sectional area than the stationary electrodes in that row.
 5. The process of claim 1 wherein rectangular shaped electrodes are introduced into the melting space of tbe mould so that the widest faces of the movably mounted electrodes face the widest faces of stationary ones. 